Sperm whale (Physeter macrocephalus)

 

 

 

Meaning of species name is "big head".

Cosmopolitan, the largest toothed-whale and record holder of  both dive depth (2 km) and dive duration (2 h) among marine mammals.

At sea identification: The largest regional cetacean and the only one demonstrating marked sexual bimorphism, males reaching 18 m and females only 11 m. The crate-shaped head is disproportionately large, especially in the mature male, where it comprises a third of the body length. Unlike other cetaceans, the skin is wrinkled. Pectoral fins are very small relative to body size and the dorsal fin is essentially lacking, being replaced by an inconspicuous hump, and trailed by a series of small ridges. Color ranges from dark grey to brown, the under part of the head showing lighter coloration.The blow is very prominent and distinctly diagonal, aimed forward and leftward. Uses a "fluke-up" dive when sounding (tailstock exposed vertically, with the under part of the flukes visible). Sperm whales dive very deep and long, up to an hour or more. Lives above the slope, but may approach close to shore over undersea canyons and cliffs. Swim speed usually 3 knots, may increase to 12.

Identifying marks on land: No room for error. Lower jaw is very narrow, with two rows of 20-25 teeth. Teeth in the upper jaw do not erupt.

The Mediterranean population is probably endemic but its social structure (especially of males) is largely unknown. The pattern of mature males roving between groups of females with calves probably holds. In other parts of the world, male calves leave the maternal pod at the age of six to form bachelor groups and may only reach physical and sexual maturity at the age of 20, at which time they may become solitary. Feeds on squid and octopus and very rarely on cartilaginous fish. Females give birth every 4-6 years after an 18 month long pregnancy. Calves may suckle for several years.

Has been acoustically spotted on June of 2005 off Ashdod and a near-term or newborn calf has beached on Hadera Port on August of 2005. Several unauthenticated but apparently credible sightings of sperm whale by fishermen and divers exist in IMMRAC's records.

Additional facts:

Weight: 57 tons for males and 24 tons for females

Newborn length is 4 meters and weight is 1 ton.

Life expectancy: 70 years.

 

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